Bourdon-tube and the bellows elements. Bourdon-
frequently monitored aboard ship. As with temper-
tube elements are suitable for the measurement
ature readings, pressure readings provide you with
of very high pressures up to 100,000 psig. The
an indication of the operating condition of equip-
upper limit for bellows elements is about 800 psig.
ment. Pressure measuring instruments that we
discuss are of three types: mechanical, electrical,
Bourdon-Tube Elements
and mechanical-electrical. The mechanical-
electrical pressure instruments are switches.
Bourdon-tube elements used in pressure
MECHANICAL PRESSURE
gauges are essentially the same as those de-
MEASURING INSTRUMENTS
scribed for use in filled-system thermometers.
Bourdon tubes for pressure gauges are made
Two of the primary mechanical pressure
of brass, phosphor bronze, stainless steel,
measuring instruments found aboard ship are the
Figure 5-12.--Simplex Bourdon-tube pressure gauge.
Figure 5-13.--Duplex Bourdon-tube pressure gauge.
5-10
